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Thread: Phosfree Clogged Filters

  1. Back To Top    #1

    Join Date
    Jul 2014

    Phosfree Clogged Filters

    I have been fighting what I think is Mustard Algae. It was recommended to lower phosphates using phosfree. So I did ... Anyway I tried.
    I following the instructions and within 4 hours the pressure on my new cartridge filter was about 30 (started at 10). I continued to let the filter run for 48 hours as instructed.

    After 48 hours, my cartridge pressure is 40. I soaked the cartridge in a Filter fresh type product, used a car wash pressure hose to clean it out and put it back on. The pressure started at 10 and then 20, 30 and soon.

    How is the heck fire can I unclogged my new $100 cartridge ?

    I should have known better because I have been bitten by phosfree before...


  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: Phosfree Clogged Filters

    Welcome to TFP!

    We recommend avoiding phos-free. Phosphates are not a problem if you maintain appropriate FC levels.

    Meanwhile, you should rinse off your filter more frequently until things return to normal. There isn't usually any long term damage to the filter.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  3. Back To Top    #3
    Richard320's Avatar
    Join Date
    Jan 2010
    San Dimas, CA (LA County)

    Re: Phosfree Clogged Filters

    Sadly, your experience is common.

    I suspect the profit margin on phos-free is really good, hence the frequent recommendation to use it.

    It's interesting how seldom the pool stores follow the Instructions. (Click to open popup)
    For DE & Cartridge Filters: Do not add more than 1.5L (48oz) at a time. If more than 1.5L (48oz) is needed to treat, be sure to clean or backwash the filter between treatments.
    Important: Algae must be treated prior to testing and lowering phosphates. Chlorine must be under 5ppm before testing phosphates.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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